Currently, only three drugs are used to control and treat the mosquito-borne parasitic disease lymphatic filariasis: diethylcarbamazine, ivermectin (Mectizan) and albendazole (Zentel). All interrupt transmission by eliminating microfilaria, the parasite stage that is responsible for transmission between hosts, but do not reliably kill the adult worms that are responsible for much of the pathology seen in the disease. There is an urgent need to develop drugs that will reliably kill adult worms and several compounds are under-going in vitro and animal testing. An alternative strategy - that of targeting symbiont bacteria within the parasite - has also shown promising results.